Ambrosia eriocentra is a North American species of ragweed known by the common names woolly bursage and woollyfruit burr ragweed. It is native to the southwestern United States (California, Arizona, Nevada, Utah), where it grows in the deserts and surrounding ridges up to about 1700 meters in elevation. Ambrosia eriocentra is a rounded shrub reaching over 1. 5 meters in height. The stems are brownish gray in color, with young twigs coated in light woolly fibers and older branches bare. Leaves are lance-shaped and up to 9 centimeters long, not counting the winged petioles. The leaves have rolled lobed or toothed edges. As in other ragweeds, the inflorescence has a few staminate (male) flower heads next to several single-flowered pistillate heads. The fruit is a green burr with long, silky white hairs and several hair-tufted sharp spines. The burr is around a centimeter long.